Готові списки джерел за темами / Oxide thin films and heterostructure

Добірка наукової літератури з теми "Oxide thin films and heterostructure"

Автор: Grafiati
Опубліковано: 6 вересня 2023

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Статті в журналах з теми "Oxide thin films and heterostructure"

1

Golan, G., A. Axelevitch, and Jacob Azoulay. "Properties investigation of thin films photovoltaic hetero-structures." World Journal of Engineering 11, no. 3 (June 1, 2014): 233–38. http://dx.doi.org/10.1260/1708-5284.11.3.233.

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Анотація:
This paper presents an experimental investigation of photovoltaic (PV) properties in heterostructures consisting of indium oxide and amorphous silicon thin films, grown on a single crystalline p-type silicon and polyimide flexible substrates. Both thin films: In2O3 and a-Si were deposited by magnetron sputtering. Such heterostructure thin film systems are attractive because of their ability to convert solar energy into electrical one. Grown Heterostructures films were treated by simultaneous influence of an electron beam and high energetic photons with energy more than 1.5 eV in the so called vacuum photo-thermal processing (VPP).Silicon samples of 100 Ω/sq and 45 Ω/sq were selected as substrates. Thin films deposition was done in argon atmosphere by DC magnetron sputtering.It is shown that:Open circuit voltage of the proposed structure may reach up to ~ 0.35 V,Short circuit current was of no more then 10-7 A,Polyimide materials may be used as substrates for PV thin film deposition structures,VPP dramatically varies the photovoltaic properties of the heterostructure
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2

Yang, Gene, Wonsang Jung, Sung-Jin Ahn, and Dongkyu Lee. "Controlling the Oxygen Electrocatalysis on Perovskite and Layered Oxide Thin Films for Solid Oxide Fuel Cell Cathodes." Applied Sciences 9, no. 5 (March 12, 2019): 1030. http://dx.doi.org/10.3390/app9051030.

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Анотація:
Achieving the fast oxygen reduction reaction (ORR) kinetics at the cathode of solid oxide fuel cells (SOFCs) is indispensable to enhance the efficiency of SOFCs at intermediate temperatures. Mixed ionic and electronic conducting (MIEC) oxides such as ABO3 perovskites and Ruddlesden-Popper (RP) oxides (A2BO4) have been widely used as promising cathode materials owing to their attractive physicochemical properties. In particular, oxides in forms of thin films and heterostructures have enabled significant enhancement in the ORR activity. Therefore, we aim to give a comprehensive overview on the recent development of thin film cathodes of SOFCs. We discuss important advances in ABO3 and RP oxide thin film cathodes for SOFCs. Our attention is also paid to the influence of oxide heterostructure interfaces on the ORR activity of SOFC cathodes.
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3

Zhu, Jiaxin, Jung-Woo Lee, Hyungwoo Lee, Lin Xie, Xiaoqing Pan, Roger A. De Souza, Chang-Beom Eom, and Stephen S. Nonnenmann. "Probing vacancy behavior across complex oxide heterointerfaces." Science Advances 5, no. 2 (February 2019): eaau8467. http://dx.doi.org/10.1126/sciadv.aau8467.

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Oxygen vacancies (VO••) play a critical role as defects in complex oxides in establishing functionality in systems including memristors, all-oxide electronics, and electrochemical cells that comprise metal-insulator-metal or complex oxide heterostructure configurations. Improving oxide-oxide interfaces necessitates a direct, spatial understanding of vacancy distributions that define electrochemically active regions. We show vacancies deplete over micrometer-level distances in Nb-doped SrTiO3 (Nb:SrTiO3) substrates due to deposition and post-annealing processes. We convert the surface potential across a strontium titanate/yttria-stabilized zirconia (STO/YSZ) heterostructured film to spatial (<100 nm) vacancy profiles within STO using (T = 500°C) in situ scanning probes and semiconductor analysis. Oxygen scavenging occurring during pulsed laser deposition reduces Nb:STO substantially, which partially reoxidizes in an oxygen-rich environment upon cooling. These results (i) introduce the means to spatially resolve quantitative vacancy distributions across oxide films and (ii) indicate the mechanisms by which oxide thin films enhance and then deplete vacancies within the underlying substrate.
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4

Zhu, Jiaxin, Jung-Woo Lee, Hyungwoo Lee, Lin Xie, Xiaoqing Pan, Roger A. De Souza, Chang-Beom Eom, and Stephen S. Nonnenmann. "Probing Vacancy Behavior in Complex Oxide Heterostructured Films." ECS Meeting Abstracts MA2018-01, no. 32 (April 13, 2018): 1931. http://dx.doi.org/10.1149/ma2018-01/32/1931.

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Анотація:
Oxygen vacancies (Vo•• ) play a critical role in the transport mechanisms within complex oxides, analogous to electrons and holes within semiconductors. Systems including memristors, all-oxide electronics, and electrochemical cells comprise substrate-supported thin films either in metal-insulator-metal or complex oxide heterostructure configurations. As well-studied defect chemistry dictates mixed electronic/ionic functionality, improving oxide-oxide interfaces necessitates a direct, spatial understanding of vacancy distributions that define electrochemically active regions. Here we show that vacancies deplete over large, micron-level distances within single crystalline perovskite Nb-doped SrTiO3 substrate (Nb:SrTiO3) substrates after typical vacuum film deposition and post-annealing processes. We demonstrate the conversion of the surface potential across a four-layer strontium titanate / yttria-stabilized zirconia (STO/YSZ) heterostructured film to spatially defined (< 100 nm) [Vo•• ] profiles within STO through a unique combination of high temperature (500 °C), in situ scanning probes and classic semiconductor energy band diagram model analysis. Further comparison between room temperature and high temperature potential profiles clearly distinguishes between electronic-dominant and activated, ionic-dominant transport characteristics within the oxide layers. Consequently, we determined that oxygen scavenging by deposited films during pulsed laser deposition significantly reduce the Nb:STO, which is then partially reoxidized in the ambient environment during cooling. The results presented herein i) introduce the means to spatially resolve quantitative vacancy distributions across oxide films, and ii) pose the mechanism by which oxide thin film getters both enhance then deplete vacancies within the underlying substrate.
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5

Itapu, Srikanth, Kamruzzaman Khan, and Daniel G. Georgiev. "Effect of UV Laser Irradiation on the properties of NiO films and ZnO/NiO Heterostructures." MRS Advances 1, no. 4 (2016): 293–98. http://dx.doi.org/10.1557/adv.2016.99.

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ABSTRACTThe present work accentuates the effect of UV laser irradiation on the conductivity of nickel oxide (NiO) thin films, deposited at various temperatures by radio-frequency reactive sputtering of Ni in oxygen containing atmosphere. The effect of UV irradiation on zinc oxide – nickel oxide heterostructures, obtained by sputtering, was examined as well. It was found that the resistivity of NiO changes from 12 Ω-cm to 0.62 Ω-cm, and the majority carrier concentration from 3.95x1017 holes/cm3 to 4.22x1020 electrons/cm3. The current-voltage (I-V) characteristics of the ZnO/NiO heterostructure shows an improved p-n diode behavior with the forward bias current increasing for the laser-irradiated ZnO/NiO compared to the as-deposited stack. The observed improvement in diode-like behavior suggests that laser irradiation can be an important technique to controllably change the structural, electrical and optical properties of metal oxide thin films.
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6

Orletskyi, I. G., M. I. Ilashchuk, E. V. Maistruk, M. M. Solovan, P. D. Maryanchuk, and S. V. Nichyi. "Electrical Properties of Sis Heterostructures n-SnS2/CdTeO3/p-CdZnTe." Ukrainian Journal of Physics 64, no. 2 (February 21, 2019): 164. http://dx.doi.org/10.15407/ujpe64.2.164.

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Анотація:
Conditions for the production of rectifying semiconductor-insulator-semiconductor (SIS) heterostructures n-SnS2/CdTeO3/p-Cd1−xZnxTe with the use of the spray-pyrolysis of SnS2 thin films on p-Cd1−xZnxTe crystalline substrates with the formation of an intermediate tunnel-thin CdTeO3 oxide layer have been studied. By analyzing the temperature dependences of the current-voltage characteristics, the dynamics of the heterostructure energy parameters is determined, and the role of energy states at the CdTeO3/p-Cd1−xZnxTe interface in the formation of forward and reverse currents is elucidated. By analyzing the capacity-voltage characteristics, the processes of charge accumulation and inversion in SIS structures is considered. An energy diagram of the examined heterostructure, which well describes experimental electro-physical phenomena, is proposed.
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7

Hamlin, Andrew Bradford, Youxiong Ye, Julia Elizabeth Huddy, and William Joseph Scheideler. "Modulation Doped 2D InOx/GaOx Heterostructure Tfts Via Liquid Metal Printing." ECS Meeting Abstracts MA2022-01, no. 31 (July 7, 2022): 1326. http://dx.doi.org/10.1149/ma2022-01311326mtgabs.

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Indium gallium zinc oxide (IGZO) and similar wide bandgap metal oxides are among the most widely used channel materials for drive transistors in displays due to their excellent electronic mobility and their ultra-high transparency1. However, industry-standard processing involves expensive vacuum deposition and elevated activation temperatures to produce semiconducting thin films. Liquid metal printing (LMP) is an emerging technique for oxide semiconductor fabrication poised to overcome these drawbacks via scalable vacuum-free transfer of the native oxide layers formed by spontaneous surface oxidation of molten metals2–4. Heterostructures of these 1-4 nm 2D oxide layers provide unprecedented opportunities for engineering electrostatic control of multilayers in thin film transistors, leading to improved mobility, Ion/Ioff ratios, and faster switching capabilities. Likewise, the backchannel is of high importance to these devices, as selection of an appropriate capping layer can enhance performance via remote doping while also mitigating bias stress effects. Herein, we compare the results of heterostructure InOx/GaOx with pure InOx TFTs, which demonstrates the mobility enhancement provided by GaOx modulation doping. Bottom gate thin film transistors (TFTs) (Figures 1a and 1b) were fabricated on Si substrates with 100 nm of thermally grown SiO2. 4 nm thick InOx and GaOx were deposited at 240 ˚C and 180 ˚C, respectively, using a linear printing speed of 8 cm/s. InOx and GaOx were printed in less than 10 s, with no post annealing necessary. Figure 1c illustrates the proposed mechanism for electron donation from GaOx at the heterointerface with InOx. The conduction band offset between these materials results in band bending at the interface and an increased carrier concentration in the InOx layer. The substoichiometric, defective GaOx is expected to further enhance this effect. Figure 1d demonstrates the transfer characteristics of heterostructure InOx/GaOx in comparison with pure InOx. The improved mobility for the heterostructure (7.8 cm2/Vs) vs pure InOx (3.8 cm2/Vs) channels can be attributed to modulation doping provided by GaOx and can be analyzed by extracting the electronic density of states (eDOS). These results illustrate a unique capability of LMP, which is to engineer the electronic structure of highly conductive 2D oxides while maintaining electrostatic control. This work also investigates the material properties of these 2D oxide heterostructures by UV-vis, XRD and XPS characterization. UV-Vis analysis revealed that the GaOx capping layer induces band gap widening and enhanced transparency, which can be explained by the Burstein-Moss effect from modulation doping. Unique to this LMP process is also the low temperature crystallization of the InOx films. XRD showed that even with low deposition temperatures (200 – 240 ˚C), these InOx films are highly crystalline with grain sizes substantially larger than the film thickness. Finally, XPS analysis of the O1s peak was utilized to understand the stoichiometry and interactions between the InOx and GaOx layers. This work demonstrates an effective pathway to enhance electronic transport in semiconducting metal oxides through liquid metal printed 2D heterostructures. The ultrathin films produced by LMP are well suited for thin film devices requiring nm-scale electrostatic control for effective gating. Combining this 2D nature of LMP InOx with a 2D GaOx backchannel capping layer is shown to yield high-performance printed transistors. This approach demonstrates a rapid, open-air compatible and low temperature manufacturing method, elucidating the broad impact of this technology in display fabrication, low-cost and flexible electronics. H. Hosono, Nat Electron, 1, 428–428 (2018). K. A. Messalea et al., ACS Nano, 15, 16067–16075 (2021). R. S. Datta et al., Nat Electron, 3, 51–58 (2020). A. Jannat et al., ACS Nano, 15, 4045–4053 (2021). A. Goff et al., Dalton Transactions, 50, 7513–7526 (2021). C.-H. Choi, Y.-W. Su, L.-Y. Lin, C.-C. Cheng, and C. Chang, RSC Advances, 5, 93779–93785 (2015). Figure 1
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Aivalioti, Chrysa, Alexandros Papadakis, Emmanouil Manidakis, Maria Kayambaki, Maria Androulidaki, Katerina Tsagaraki, Nikolaos T. Pelekanos, et al. "Transparent All-Oxide Hybrid NiO:N/TiO2 Heterostructure for Optoelectronic Applications." Electronics 10, no. 9 (April 21, 2021): 988. http://dx.doi.org/10.3390/electronics10090988.

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Анотація:
Nickel oxide (NiO) is a p-type oxide and nitrogen is one of the dopants used for modifying its properties. Until now, nitrogen-doped NiO has shown inferior optical and electrical properties than those of pure NiO. In this work, we present nitrogen-doped NiO (NiO:N) thin films with enhanced properties compared to those of the undoped NiO thin film. The NiO:N films were grown at room temperature by sputtering using a plasma containing 50% Ar and 50% (O2 + N2) gases. The undoped NiO film was oxygen-rich, single-phase cubic NiO, having a transmittance of less than 20%. Upon doping with nitrogen, the films became more transparent (around 65%), had a wide direct band gap (up to 3.67 eV) and showed clear evidence of indirect band gap, 2.50–2.72 eV, depending on %(O2-N2) in plasma. The changes in the properties of the films such as structural disorder, energy band gap, Urbach states and resistivity were correlated with the incorporation of nitrogen in their structure. The optimum NiO:N film was used to form a diode with spin-coated, mesoporous on top of a compact, TiO2 film. The hybrid NiO:N/TiO2 heterojunction was transparent showing good output characteristics, as deduced using both I-V and Cheung’s methods, which were further improved upon thermal treatment. Transparent NiO:N films can be realized for all-oxide flexible optoelectronic devices.
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9

Lu, Chengliang, Weijin Hu, Yufeng Tian, and Tom Wu. "Multiferroic oxide thin films and heterostructures." Applied Physics Reviews 2, no. 2 (June 2015): 021304. http://dx.doi.org/10.1063/1.4921545.

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Perret, Edith, Changyong Park, Dillon D. Fong, Kee-Chul Chang, Brian J. Ingram, Jeffrey A. Eastman, Peter M. Baldo, and Paul H. Fuoss. "Resonant X-ray scattering studies of epitaxial complex oxide thin films." Journal of Applied Crystallography 46, no. 1 (January 17, 2013): 76–87. http://dx.doi.org/10.1107/s0021889812047620.

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Анотація:
Resonant anomalous X-ray reflectivity (RAXR) is a powerful technique for measuring element-specific distribution profiles across surfaces and buried interfaces. Here, the RAXR technique is applied to characterize a complex oxide heterostructure, La0.6Sr0.4Co0.2Fe0.8O3−δ, on NdGaO3, and the effects of data sampling and model-dependent fitting procedures on the extracted elemental distribution profile are evaluated. The strontium profile through a 3.5 nm-thick film at 973 K and at an oxygen partial pressure of 150 Torr (1 Torr = 133.32 Pa) was determined from the measured RAXR spectra. The results demonstrate thatin situRAXR measurements can provide key insights into temperature- and environment-dependent elemental segregation processes, relevant, for example, in assessing the cathode performance of solid oxide fuel cells.
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Більше джерел

Дисертації з теми "Oxide thin films and heterostructure"

1

Glavic, Artur [Verfasser]. "Multiferroicity in oxide thin films and heterostructures / Artur Glavic." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2012. http://d-nb.info/1025883497/34.

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2

Vaghefi, Seyedeh Pegah Mirzadeh. "Structural and physical properties studies on multiferroic oxide films and heterostructures." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/18502.

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Doutoramento em Engenharia Física
O presente trabalho de doutoramento é um estudo de propriedades físicas e aspectos estruturais de filmes de óxidos e heteroestruturas multiferróicas, englobando técnicas de caracterização do nível macroscópico ao microscópico. O objectivo principal é a compreensão de novas heteroestruturas epitaxiais multifuncionais e as suas interfaces para junções de túnel magnetoelétricas e filtros de spin. Os principais materiais em estudo foram manganitas à base de La dopadas com iões divalentes (ba, Sr), apresentando efeito magnetoelétrico, sendo preparadas em diferentes substratos e diferentes técnicas de crescimento, optimizadas para epitaxia e qualidade de interface. O estudo combinado de propriedades eléctricas e magnéticas permitiu estabelecer as condições necessárias para a aplicação dos materiais multiferróicos em estudo, por técnicas experimentais apresentadas neste trabalho. O trabalho consistiu no estudo sistemático de microestrutura de filmes finos de La0:7Sr0:3MnO3 em substratos de SrTiO3, preparados por pulsed laser deposition, o filme fino de La0:9Ba0:1MnO3 e a heteroestrutura La0:9Ba0:1MnO3/BaTiO3/La0:9Ba0:1MnO3 em substrato de Al2O3, e filme fino de La0:9Ba0:1MnO3, BaTiO3 e heteroestrutura de La0:9Ba0:1MnO3/BaTiO3/La0:9Ba0:1MnO3 em substrato de Si, preparado por RF magnetron sputtering. A caracterização estrutural das amostras foi feita principalmente por difracção de raio-X (XRD) convencional e de alta resolução e Microscopia de Transmissão de Alta Resolução (HRTEM). A composição química foi analisada por Electron Dispersion Spectroscopy (EDS), Rutherford backscattering spectroscopy (RBS) e energy filtered transmission electron microscopy (EFTEM). As medidas de magnetização forram realizada com a um magnetómetro superconducting quantum interference device (SQUID). A análise da topografia e efeitos locais foi realizada por microscopia de varimento de ponta usando microscopia da Força Atómica (AFM) e de resposta piezoeléctronica (PFM). Os resultados mostram claramente uma evolução da microestrutura dos filmes finos de La0:7Sr0:3MnO3, á medida que aumenta a sua espessura, passando de uma estrutura policristalina no filme mais fino (13.5 nm) a colunar inclinado (45 nm e 200 nm), a uma estrutura ramificada no filme mais espesso (320 nm). A alteração na estrutura do filme é devida à tensão pelo substrato e deformação da estrutura nas etapas iniciais de crescimento, onde se detectaram fronteiras anti-phase e maclas. A evolução da estrutura modificou as propriedades magnéticas dos filmes a baixa temperatura (abaixo da temperatura de transição estrutural do substrato de SrTiO3), mostrando magnetização em excesso e defeito, para espessuras abaixo e acima de 100 nm, respectivamente. Análises STEM-EELS e EFTEM mostraram a diferença em composição elementar dos filmes perto das fronteiras e na interface com o substrato.No âmbito do plano de trabalhos de doutoramento, o segundo substrato consiste em estudar as propriedades físicas e estruturais de filmes finos de La0:9Ba0:1MnO3 e heteroestruturas La0:9Ba0:1MnO3/BaTiO3/La0:9Ba0:1MnO3 em substratos de Al2O3, revelando estruturas altamente orientadas. A razão La/Ba do filme e heteroestrutura é drasticamente diferente do alvo providenciado, La0:7Ba0:3MnO3, como provado por XRD, RBS e transições de fase magnéticas. As propriedades magnéticas e eléctricas das estruturas mostraram uma forte dependência na cristalinidade do filme e da heteroestrutura. A parte final do trabalho é dedicada aos filmes de La0:9Ba0:1MnO3, BaTiO3 e a heteroestrutura de La0:9Ba0:1MnO3/BaTiO3/La0:9Ba0:1MnO3 em substrato de Si, que em comparação com as estruturas em substrato de ALO, provaram o efeito da cristalinidade nas propriedades magnéticas, eléctricas e de magneto-resistência do filme e heteroestrutura. Foi mostrado que um grau superior de cristalinidade leva a uma mais elevada magnetização, reduzindo a resistividade das estruturas. Pela primeira vez, um estudo de deformação de topografia por aplicação de uma tensão dc externa foi feito num filme fino de BaTiO3 em Si, usando uma técnica de poling num microscópio de força piezoresponse. Os resultados mostraram a capacidade de uma modificação controlada da superfície, por aplicação de uma voltagem externa nointervalo 14V < Vapp < 20V. Abaixo destes valores, não se observou alguma deformação na topografia, enquanto acima deste intervalo, a 30V, a superfície foi completamente danificada. A mudança topográfica produzida mostrou estabilidade no tempo, onde após a aplicação de 20V, a área modificada alcançou 83% da altura as-poled ( 9 nm) em 90 minutos, a 7,4 nm. A resposta assimétrica de piezoresponse da área poled foi associada à existência de um campo eléctrico interno na amostra, que foi também provado através de medidas de espectroscopia de switching no filme fino. A heteroestrutura no substrato de Si mostraram o mesmo fenómeno que a mono-camada de BaTiO3, onde o arranjo de heteroestrutura realça o efeito de voltagem aplicada na topografia. Aplicando 10V, a estrutura da superfície foi alterada na heteroestrutura e houve uma modificação visível da camada de BaTiO3, alterando também a topografia da camada superior de La0:9Ba0:1MnO3.
This present PhD work made a study of structural aspects and physical properties of the oxide films and multiferroic heterostructures, encompassing the techniques from macroscopic level to microscopic description. The understanding of novel multifunctional epitaxial heterostructures and their interfaces for magneto-electrically driven tunnel junctions and spin-filters is the central objective. The main materials in study were La based doped manganites with magnetoelectric effect prepared on different substrates and growth conditions, optimized for epitaxy and interface quality. The combined study of electric and magnetic properties allowed us examining the conditions required for application of the studied multiferroic materials and experimental techniques are presented in this work. The work consists of three main substrates, a systematic study of microstructure of La0:7Sr0:3MnO3 thin films on SrTiO3 substrate, prepared by pulsed laser deposition, the La0:9Ba0:1MnO3 thin film and La0:9Ba0:1MnO3/BaTiO3/La0:9Ba0:1MnO3 heterostructure on Al2O3 substrate, and the La0:9Ba0:1MnO3 thin film, BaTiO3 and La0:9Ba0:1MnO3/BaTiO3/La0:9Ba0:1MnO3 heterostructure on Si substrate, prepared by RF magnetron sputtering. Main structural characterization of samples was performed by conventional and high resolution X-Ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM); chemical composition was determined by Electron Dispersion Spectroscopy (EDS), Rutherford Backscattering Spectroscopy (RBS) and Energy Filtered Transmission Electron Microscopy (EFTEM); Magnetization measurements done with a Superconducting Quantum Interface Device (SQUID) magnetometer. Surface probing of topography and local effects was performed, using Atomic Force (AFM) and Piezo-Response (PFM) Microscopy. Results clearly showed that there is an evolution in the microstructure of the La0:7Sr0:3MnO3 thin films, by increasing their thickness, changing from polycrystalline structure in the thinnest film (13.5 nm) to tilted columnar structure(45 nm and 200 nm) and to a branched structure in the thickest film (320 nm). The change in the structure of the film is due to the strain from the substrate and deformation of the structure in the early stages of the growth, where anti-phase boundaries and twinning were detected. The evolution of the structure modified the low temperature (below structural phase transition of SrTiO3 substrate) magnetic properties of the films, showing in-excess and in-defect magnetization, below and above 100 nm thickness, respectively. Also, STEM-EELS and EFTEM analysis showed the difference in the elemental composition of the films near the boundaries and interface with the substrate.In the scope of the PhD work plan, the second substrate consists of studying the structural and physical properties of La0:9Ba0:1MnO3 thin film and La0:9Ba0:1MnO3/BaTiO3/La0:9Ba0:1MnO3 heterostructure on Al2O3 substrate, where they showed highly oriented structure. The La/Ba ratio of the single layer film and heterostructure is drastically different from the target, La0:7Ba0.3MnO3, proven by XRD, RBS, and magnetic phase transitions. The magnetic and electrical properties of the structures showed strong dependence on the crystallinity of the samples. The final part of the work is devoted to the La0:9Ba0:1MnO3 and BaTiO3 thin films and La0:9Ba0:1MnO3/BaTiO3/La0:9Ba0:1MnO3 heterostructure on Si substrate, which in comparison with the structures on Al2O3 substrate, highlights the influence of crystallinity on magnetic, ferro-electrical and magnetoresistance properties of the film and heterostructure. It is shown that higher degree of crystallinity leads to higher magnetization and lowers the resistivity. For the first time, a study of the topography deformation by applying a dcexternal voltage was done on BaTiO3 thin film on Si, using a poling technique in a piezoresponse force microscope. The results show the ability of controlled modification of the surface, by applying an external voltage/electric field in the range of 14V< Vapp<20V. Below this range, no deformation is observed on the topography, and above this interval, at 30V, the surface is completely damaged. The produced topographical change show stabilization in respect to time, where after applying 20V, the modified area reaches its 83% of the as-poled height ( 9nm) in 90 minutes, to 7.4 nm. The asymmetrical response in the piezoresponse of the poled area is related to the existence of an internal built-in electric field in the sample, which is also confirmed by performing switching spectroscopy measurements on the single layer. The heterostructure on the Si substrate shows the same phenomena, as the BTO single layer, where the heterostructure arrangement enhances the applied voltage effect on the topography. With applying 10V, the structure of the surface changes in the heterostructure and a visible modification of BaTiO3 layer, changing also the topography of La0:9Ba0:1MnO3 top layer is observed.
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3

Leung, Gong Wai. "Magnetic semiconducting oxide thin films and heterostructures by pulsed laser deposition." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609286.

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4

Wang, Chao-Hsiung. "The growth of thin film epitaxial oxide-metal heterostructures." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368667.

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5

Lüders, Ulrike Anne. "Development and integration of oxide spinel thin films into heterostructures for spintronics." Doctoral thesis, Universitat Autònoma de Barcelona, 2005. http://hdl.handle.net/10803/3373.

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En esta memoria se describe el crecimiento, mediante pulverización catódica rf, de capas delgadas de NiFe2O4 y CoCr2O4 sobre distintos substratos y la subsiguiente caracterización magnética y eléctrica. El objetivo es integrar dichas capas en dispositivos magnetoelectrónicos tales como uniones túnel o filtros de spin.
Hemos descubierto que el crecimiento epitaxial permite estabilizar fases nuevas del óxido NiFe2O4, fases que no existen en la forma másiva, y que tienen propiedades remarcablemente distintas. Como por ejemplo: un aumento dramático de la magnetización o la posibilidad de modificar drásticamente sus propiedades de transporte, pudiéndose obtener capas aislantes -como es en forma cerámica- o conductivas. Se ha realizado un estudio sistemático de los efectos del espesor de la capa y de las condiciones de crecimiento sobre las propiedades de magnetotransporte y los mecanismos de crecimiento.
Argumentamos que el aumento de la magnetización es debido a la estabilización de una fase NiFe2O4 espinela que es parcialmente inversa, en la que los iones Ni2+ están distribuidos entre las dos posiciones disponibles (tetraédrica y octaédrica) de la estructura. En la forma masiva del material los iones Ni solo se encuentran en los sitios octaédricos. La introducción adicional de vacantes de oxígeno es probablemente la causa de la existencia de una configuración electrónica mixta Fe2+/3+ en la subred octaédrica y de la alta conductividad de las capas.
Hemos aprovechado la capacidad de obtener epitaxias de NiFe2O4 ferrimagnéticas conductoras o aislantes para integrarlas en dos distintos dispositivos magnetoelectrónicos: una unión túnel magnética y un filtro de spin.
Las capas conductoras de NiFe2O4 se han empleado como electrodos ferrimagnéticos-metálicos en uniones túnel. El otro electrodo magnético es (La,Sr)MnO3 y la barrera túnel SrTiO3. Se ha podido medir una magnetoresistencia túnel importante hasta temperaturas tan altas como 280K. Los valores de magnetoresistencia corresponden a una polarización de spin del NiFe2O4 de aproximadamente un 40%, que es prácticamente independiente de la temperatura. Estos resultados sugieren que la nueva fase conductora que hemos estabilizado es un candidato interesante como fuente de corriente polarizada en spin.
Por otra parte, el NiFe2O4 aislante se ha implementado, por primera vez, como barrera túnel en una heteroestructura de filtro de spin. El electrodo magnético es (La,Sr)MnO3 y el electrodo no magnético Au. Hemos observado una magnetoresistencia túnel que alcanza valores de hasta un 50%. A partir de estas medidas, hemos deducido detalles relevantes de la estructura electrónica de la fase parcialmente inversa de NiFe2O4.
Hemos crecido el óxido CoCr2O4 sobre distintos substratos, tales como MgO(001) y MgAl2O4(001). Hemos podido comprobar que este óxido presenta una pronunciada tendencia a un crecimiento 3D. Por esta razón, las superficies de la capa no son nunca suficientemente planas y no se pueden usar en heteroestructuras túnel.
Sin embargo hemos aprovechado esta característica para controlar el crecimiento de estas estructuras 3D y hemos conseguido la formación de objetos submicrónicos, autoorganizados con formas piramidales muy bien definidas. El estudio detallado del efecto de los parámetros de crecimiento nos ha permitido por una parte, dilucidar cuales son los mecanismos que llevan a una autoorganización tan perfecta y por otra determinar que, en las condiciones adecuadas, se pueden obtener templates totalmente faceteados con múltiples posibilidades para futuras aplicaciones.
In this thesis the growth of thin films of NiFe2O4 and CoCr2O4 by RF sputtering on different oxide substrates and the characterization of their magnetic and electric properties is reported. The aim is to integrate the films into spintronic devices namely magnetic tunnel junctions and spin filter.
It was found that the epitaxial growth of these films permits to stabilize new phases of NiFe2O4, which are not found for the bulk material and which show remarkably distinct properties. A strong enhancement of the saturation magnetization was found as well as the possibility to tune the electric behaviour of the films from insulating - like in bulk NiFe2O4 - to conducting. A systematic study of the influence of the film thickness and growth parameters on the properties of the films was carried out.
The enhancement of the saturation magnetization can be explained by a partially inversed spinel structure, where the Ni2+ ions are distributed over both available sites (octahedral and tetrahedral) of the structure, whereas in bulk NiFe2O4 the Ni2+ ions are only located on the octahedral sites of the structure. An additional introduction of oxygen vacancies causes the formation of mixed valence Fe2+/3+ chains on the octahedral sites and thus a hopping conductivity.
We have taken advantage of our ability to obtain epitaxial ferromagnetic NiFe2O4 films of insulating or conducting character to integrate them in two different spintronic devices: the magnetic tunnel junction and the spin filter.
The conducting NiFe2O4 was integrated in a magnetic tunnel junction as a magnetic electrode, with a (La,Sr)MnO3 counterelectrode and a SrTiO3 barrier. A magnetoresistance was measured up to a temperature of 280K. The values of the magnetoresistance correspond to a spin-polarization of 40%, which is basically constant in temperature. This results show that the conductive phase of NiFe2O4 is an interesting candidate for the application as a source of highly spin-polarized current.
On the other hand the insulating NiFe2O4 has been integrated into a spin filter as the magnetic barrier. The magnetic electrode was again (La,Sr)MnO3 and the counter electrode Au. A magnetoresistance up to 50% was observed. It was possible to deduce the band structure of NiFe2O4 from these measurements.
Thin films of CoCr2O4 were grown on different substrates like MgO(001) or MgAl2O4(001). It was found that the material shows a pronounced tendency to grow in a three dimensional manner. Thus the surface of these films is not sufficiently smooth to integrate them into tunnel contacts.
However, we were able to control the growth and morphology of the three dimensional structures leading to the formation of submicron self-organized pyramids with a square or elongated base. By a detailed study of the influence of the growth parameters it was possible to elucidate the underlying growth mechanisms and to obtain a fully faceted surface, which can be used in different applications.
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6

Luders, Ulrike. "Development and integration of oxide spinel thin films into heterostructures for spintronics." Phd thesis, INSA de Toulouse, 2005. http://tel.archives-ouvertes.fr/tel-00011342.

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Des couches minces à base de NiFe2O4 et CoCr2O4 ont été réalisées par pulvérisation cathodique sur des substrats d'oxydes, dans le but de les intégrer dans des hétérostructures pour l'électronique de spin.
Il a été montré que la croissance épitaxiale permet la stabilisation de nouvelles phases de NiFe2O4 qui n'existent pas sous forme massive. Ces phases présentent une augmentation forte du moment magnétique ou la possibilité d'ajuster les propriétés électriques du matériaux. Nous expliquons l'augmentation du moment magnétique par une inversion partielle des sites cationiques du NiFe2O4, matériau dans lequel les ions Ni2+ sont répartis entre les deux sites de la structure spinelle. Les lacunes en oxygène sont susceptibles de favoriser un comportement conducteur en induisant des états de valence mixte Fe2+/3+ dans les sites octaédriques.
Des couches minces de NiFe2O4 conducteur ont été utilisées comme électrodes ferrimagnétiques dans des jonctions tunnel. Une magnétorésistance significative a été mesurée, correspondant à une polarisation de spin de 40% du NiFe2O4 pratiquement constante en température. Le NiFe2O4 isolant a été incorporé avec succès en tant que barrière tunnel ferrimagnétique au sein de jonctions de type "filtre à spin", ce qui en fait la première structure de ce type réalisée avec des oxydes complexes.
Il a été mis en évidence que les couches minces de CoCr2O4 ont une tendance forte à croître de manière tridimensionnelle de la forme des objets pyramidaux aux facettes parfaitement définies. Cette croissance auto-organisée de nano-objets et sa dépendance à l'égard des conditions de dépôt été étudie en detail.
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Sacco, Chiara. "Growth and characterization of epitaxial oxide-based electron and hole-doped thin films and their heterostructures." Doctoral thesis, Universita degli studi di Salerno, 2018. http://hdl.handle.net/10556/3180.

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2016 - 2017
The main goal of this dissertation is the study of the effects induced by quantum confinement in transition-metal oxides quantum wells (QWs). The field of possible applications of oxide-based heterostructures (oxide-based nanoelectronics, spintronics, quantum computation, excitonic devices, energy conversion in solar cells, etc.) is very ample and growing, thanks to the many fascinating and exotic properties of transition-metal oxides and their versatility as well. p-type SrMnO3/La0.7Sr0.3MnO3/SrMnO3 QWs and n-type SrCuO2/Sr0.9La0.1CuO2/SrCuO2 QWs have been studied. The first part of my work has been devoted to the investigation of quantum confinement achievement using a Mott insulator with a small band gap. The observed results suggest that this type of material can be successfully used in QWs. As a final result of my work, the achievement of dimensional effects induced by the layering on the normal state of both investigated systems (n and p-doped) has been assessed. In addition, the layering has been shown to influence the superconducting state of the investigated n-doped QWs and on the metal-to-insulator transition of the p-doped QWs. The investigation of the behavior of each layer constituent the QW (both n and p-doped) is relevant in view of future growth of proximate p-n doped systems. Part of my work, therefore, has been devoted to the study of the properties of (Sr,La)CuO2 thin films. The study of electrical transport properties of SLCO thin films as a function of the doping has allowed to relate the presence of the low temperature upturn in the (Sr,La)CuO2 resistivity versus temperature curves the quantum interference effects produced by weak localization effects. Furthermore, the presence of low temperature Fermi liquid behaviors in SLCO thin films has also been observed... [edited by Author]
XVI n.s. (XXX ciclo)
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8

Mirjolet, Mathieu. "Transparent Conducting Oxides Based on Early Transition Metals: From Electrical and Optical Properties of Epitaxial Thin Films, to Integration in All-Oxide Photoabsorbing Heterostructures." Doctoral thesis, Universitat Autònoma de Barcelona, 2021. http://hdl.handle.net/10803/673687.

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Els òxids conductors transparents (TCO) són essencials en dispositius tecnològics. La seva capacitat per combinar una alta conductivitat elèctrica i transparència òptica a la llum visible, els fa particularment útils en una gran varietat de dispositius: pantalles, cèl·lules solars, finestres intel·ligents, etc. L’òxid d’indi i estany (ITO) és fins ara el TCO més estès. Un gran inconvenient de l’ITO és el seu alt cost ja que l’indi, el seu component principal, és un material escàs. D’altra banda, alguns òxids metàl·lics intrínsecs de metalls de transició també són transparents. En aquests materials, la banda (3,4)d és estreta i parcialment plena. És la responsable de l’alta densitat de portadors lliures i la seva massa efectiva gran fa que la llum no es reflecteixi en el visible i que el llindar de reflexió (freqüència de plasma) estigui a la regió de l’IR proper. En aquesta tesi, hem explorat les propietats de les pel·lícules primes d’òxids metàl·lics (SrVO3 (SVO; 3d1) i SrNbO3 (SNO; 4d1)) crescudes per deposició de làser polsat (PLD). Atès que la qualitat epitaxial és fonamental per obtenir bones propietats funcionals, el primer pas va consistir en optimitzar els paràmetres de creixement de les pel·lícules SVO/SNO. Les pel·lícules han de créixer en ultra alt buit (UHV) per estabilitzar l’estat d’oxidació 4+ de V/Nb i usar temperatures de dipòsit altes (700-800° C) per permetre la mobilitat de les espècies sobre el substrat. No obstant això, l’ablació a UHV i l’expansió de la ploma del PLD, molt enèrgica, provoquen la creació de defectes puntuals en les pel·lícules. Hem resolt aquest problema utilitzant un gas inert durant el creixement, que controla l’expansió de la ploma. Finalment, hem estudiat l’impacte de la deformació epitaxial en la conductivitat elèctrica i transparència òptica. Es van obtenir pel·lícules amb una conductivitat més gran que ITO i una transparència similar. D’altra banda, l’observació que la freqüència de plasma en aquests materials estigui a l’IR proper, s’atribueix comunament a un augment de la massa efectiva dels electrons degut les correlacions e-e dins de la banda estreta 3d. Després d’una anàlisi sistemàtica de les dades de transport de SVO vam arribar a la conclusió que la teoria del líquid de Fermi no pot explicar l’augment de la massa efectiva dels portadors. En canvi, hem suggerit que l’acoblament electró-fonó i el caràcter 2D de la superfície de Fermi són molt importants. A més, hem demostrat que la imatge clàssica de banda rígida, d’un electró lliure que evoluciona en una banda 3d-t2g, és només una aproximació, com ho demostra la hibridació observada dels orbitals V 3d i O 2p. Hem observat també que la tensió epitaxial, afecta la hibridació, l’ordre orbital i últimament a la resistivitat de les capes. Hem pogut observar i explicar que a la freqüència de plasma s’exciten, en les condicions d’il·luminació adequades, plasmons de volum. Una observació i descripció poc freqüents i que, en essència, estan relacionades amb la component π de la polarització de la llum i el gradient de càrrega en la superfície del material. Finalment, hem provat la idoneïtat de SVO com elèctrode en heteroestructures fotoabsorbents “tot-òxids”. Hem observat la resposta fotovoltaica, usant capes epitaxials de LaFeO3 com absorbent, i hem posat en relleu el paper de la funció de treball de l’elèctrode en el rendiment del dispositiu. Com perspectiva, hem demostrat que els elèctrodes transparents desenvolupats (SVO i SNO), en tenir funcions de treball diferents, poden permetre ajustar i optimitzar els dispositius. Aquest treball aporta un nou coneixement fonamental de les propietats d’òxids i demostra la seva versatilitat en component fotovoltaics.
Los óxidos conductores transparentes (TCO) son esenciales en dispositivos tecnológicos. Su capacidad para combinar alta conductividad eléctrica y transparencia óptica a la luz visible los hace particularmente útiles en una gran variedad de dispositivos: pantallas, células solares, ventanas inteligentes, etc. El óxido de indio y estaño (ITO) es hasta ahora el TCO más extendido. Un gran inconveniente del ITO es su alto coste ya que el indio, su componente principal, es un material escaso. Por otro lado, algunos óxidos metálicos intrínsecos de metales de transición también son transparentes. En estos materiales, la banda (3,4)d es estrecha y parcialmente llena. Es la responsable de la alta densidad de portadores libres y su masa efectiva grande hace que la luz no se refleje en el visible y que el borde de reflexión (frecuencia de plasma) esté en la región del IR cercano. En esta tesis, hemos explorado las propiedades de las películas delgadas de óxidos metálicos (SrVO3 (SVO; 3d1) y SrNbO3 (SNO; 4d1)) crecidas por deposición de láser pulsado (PLD). Dado que la calidad epitaxial es fundamental para obtener buenas propiedades funcionales, el primer paso consistió en optimizar los parámetros de crecimiento de las películas SVO/SNO. Las películas deben crecerse en ultra alto vacío (UHV) para estabilizar el estado de oxidación 4+ de V/Nb y usar temperaturas de depósito altas (700-800°C) para permitir la movilidad de las especies sobre el sustrato. Sin embargo, la ablación en UHV y la expansión de la pluma del PLD, muy enérgica, provocan la creación de defectos puntuales en las películas. Hemos resuelto este problema utilizando un gas inerte durante el crecimiento, que controla la expansión de la pluma. Finalmente, hemos estudiado el impacto de la deformación epitaxial en la conductividad eléctrica y la transparencia óptica. Se obtuvieron películas con una conductividad mayor que ITO y una transparencia similar. Por otra parte, la observación de que la frecuencia de plasma en estos materiales esté en el IR cercano, se atribute comúnmente a un aumento de la masa efectiva de los electrones debido a las correlaciones e-e dentro de la banda estrecha 3d. Tras un análisis sistemático de los datos de transporte de SVO llegamos a la conclusión de que la teoría del líquido de Fermi no puede explicar el aumento de la masa efectiva de los portadores. En cambio, hemos sugerido que el acoplamiento electrón-fonón y el carácter 2D de la superficie de Fermi juegan un papel importante. Además, hemos demostrado que la imagen clásica de banda rígida, de un electrón libre que evoluciona en una banda 3d-t2g es solo una aproximación, como lo demuestra la hibridación observada de los orbitales V-3d y O-2p. Hemos observado también que la tensión epitaxial, afecta a la hibridación, el orden orbital y últimamente a la resistividad de las capas. Hemos podido observar y explicar que a la frecuencia de plasma se excitan, en las condiciones de iluminación adecuadas, pasmones de volumen. Una observación y descripción poco frecuentes y que, en esencia, están relacionadas con la componente π de la polarización de la luz y el gradiente de carga en la superficie del material. Finalmente, hemos probado la idoneidad de SVO como electrodo en heteroestructuras fotoabsorbentes “todo-óxido”. Hemos observado la respuesta fotovoltaica, usando capas epitaxiales de LaFeO3 como absorbente y hemos puesto de relieve el papel de la función de trabajo del electrodo en el rendimiento del dispositivo. Como perspectiva, hemos demostrado que los electrodos transparentes SVO y SNO, al tener funciones de trabajo distintas, podrán permitir ajustar y optimizar los dispositivos. Este trabajo aporta un nuevo conocimiento fundamental de las propiedades de óxidos y demuestra su versatilidad en componentes fotovoltaicos.
Transparent conducting oxides (TCOs) are key elements to many technological devices. Their ability to combine high electrical conductivity and high optical transparency to visible light, make them particularly useful in a myriad of devices such as displays, solar cells, smart windows, etc. Indium tin oxide (ITO) is so far the most widespread TCO. By Sn-doping, this wide band gap In2O3 semiconductor can reach low resistivity (only about two orders of magnitude above conventional metals) while preserving its transparency. A major drawback of ITO is its high cost as indium, its main component, is a scarce material. Moreover, due to its nature of doped-semiconductor, some physical limits impose that its properties cannot be further improved. On the other hand, some intrinsic metallic oxides composed of early transition metals also turn out to be transparent. In these materials, the partially filled narrow d band is responsible for high density of free carriers with increased effective mass, thus bringing the reflection edge down to the near-IR region. In this thesis, we were interested in exploring the properties of metallic oxide thin films grown by pulsed laser deposition (PLD), namely SrVO3 (SVO; 3d1) and SrNbO3 (SNO; 4d1). As high epitaxial quality is essential to obtain good functional properties, the first step consisted in optimizing the growth parameters for single phase and flat SVO/SNO films, displaying high crystallinity, conductivity and transparency. As anticipated, films need to be grown in ultra-high vacuum (UHV) to stabilize the 4+ oxidation state of V/Nb and using a high substrate temperature (700-800°C) to allow good mobility of the species on the substrate. However, the deposition in UHV and its subsequent highly energetic PLD plasma plume lead to a high concentration of point defects. We have solved this issue by using an inert background gas. Finally, we have studied the impact of epitaxial strain on the electrical conductivity and optical transparency window. All in all, it turned out that optimal films display larger conductivity than ITO, for a similar transparency. Conventional wisdom would suggest that a low plasma frequency would be due to the electron-electron correlations within the narrow nd1 band. In a systematic analysis of SVO transport data (temperature-dependent resistivity, etc.), we have concluded that the Fermi liquid theory alone cannot account for the carrier mass enhancement. Instead, we have suggested that the 2D-like Fermi surface and the electron-phonon coupling play a major role. In addition, we have shown that the classical rigid band picture, of one free electron evolving in a 3d-t2g band is only a rough approximation, as attested by the observed hybridization of the V 3d and O 2p orbitals. Moreover, strain affects this hybridization by modifying the orbital hierarchy and covalency which could be responsible for the observed strain-dependent resistivity and effective mass. By appropriate optical measurements, we have also discussed the nature of the plasmonic excitations at plasma frequency in SNO and SVO films. Interestingly, the possibility of exciting volume plasmons in these TCOs gives a glimpse on their potential applications in the field of plasmonics. Finally, we have tested the suitability of SVO as electrode in photoabsorbing all-oxide heterostructures. In particular, we have successfully observed a photovoltaic effect in LaFeO3-based capacitors and disclosed the important role of the electrode work function on the device performances. As outlook, we have concluded that SVO and SNO, by having distinct work functions, could allow to tune any device properties. This work demonstrates the suitability and high potential of this whole new category of TCOs as electrode material in all-oxide devices. We are convinced that it opens the way to a plethora of possible devices, photovoltaic-wise or other.
Universitat Autònoma de Barcelona. Programa de Doctorat en Física
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Mukherjee, Devajyoti. "Growth and Characterization of Epitaxial Thin Films and Multiferroic Heterostructures of Ferromagnetic and Ferroelectric Materials." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3622.

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Multiferroic materials exhibit unique properties such as simultaneous existence of two or more of coupled ferroic order parameters (ferromagnetism, ferroelectricity, ferroelasticity or their anti-ferroic counterparts) in a single material. Recent years have seen a huge research interest in multiferroic materials for their potential application as high density non-volatile memory devices. However, the scarcity of these materials in single phase and the weak coupling of their ferroic components have directed the research towards multiferroic heterostructures. These systems operate by coupling the magnetic and electric properties of two materials, generally a ferromagnetic material and a ferroelectric material via strain. In this work, horizontal heterostructures of composite multiferroic materials were grown and characterized using pulsed laser ablation technique. Alternate magnetic and ferroelectric layers of cobalt ferrite and lead zirconium titanate, respectively, were fabricated and the coupling effect was studied by X-ray stress analysis. It was observed that the interfacial stress played an important role in the coupling effect between the phases. Doped zinc oxide (ZnO) heterostructures were also studied where the ferromagnetic phase was a layer of manganese doped ZnO and the ferroelectric phase was a layer of vanadium doped ZnO. For the first time, a clear evidence of possible room temperature magneto-elastic coupling was observed in these heterostructures. This work provides new insight into the stress mediated coupling mechanisms in composite multiferroics.
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DRERA, GIOVANNI. "ELECTRONIC STRUCTURE OF TIO2 THIN FILMS AND LAALO3-SRTIO3 HETEROSTRUCTURES: THE ROLE OF TITANIUM 3D1 STATES IN MAGNETIC AND TRANSPORT PROPERTIES." Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/168728.

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The scope of this Thesis is the study of the electronic structure of two Ti-based oxide systems, TiO2 thin films and the ultra-thin LaAlO3-SrTiO3 (LAO-STO) heterojunctions, which display remarkable physical phenomena, so far not completely understood. In both cases, the titanium-related electronic states are expected to play a fundamental role and thus have been probed by means of X-ray photoemission spectroscopies. A weak room-temperature ferromagnetism (FM) has been recently detected in slightly reduced TiO2 thin film and in other oxides, such as HfO2 and CaO; since these materials are insulating closed-shell systems, this phenomenon has been classified as "d0 magnetism". Magnetism in these compounds seems to be related to the growth methodology and ultimately to the presence of structural defects, such as oxygen vacancies. Therefore, a thorough analysis of titanium electronic states, and especially of the defect-related Ti3+ energy levels, is needed in order to understand the origin of magnetic interactions. In the first part of this Thesis, a comprehensive magnetic characterization of a set of TiO2 samples is given, together with the analysis of Ti 3d-related states carried out with X-ray photoemission (XPS) and resonant photoemission (ResPES). A set of N-doped TiO2 thin films have also been grown, in order to verify the effect of doping on the TiO2 magnetism. The hypothesis of a clustered oxygen-vacancies origin of FM is then discussed in the light of the experimental and theoretical results. Another interesting oxide system in which the stoichiometry of Ti ions play a fundamental role is the LAO-STO interface. LAO and STO, separately, are two band insulators, with an empty shell electronic structure (3d0 for STO, 4f0 for LAO) and a similar perovskite structure; however, the interface created by growing LAO on the top of STO (001) has found to become metallic, hosting a 2D electron gas. This heterostructure becomes conductive only when the STO is terminated with a TiO2 layer; therefore, the Ti-related electronic states are expected to host the metallic states. The second part of this Thesis is devoted to the study of conductive and insulating LAO-STO interfaces, carried out by XPS, X-ray absorption (XAS) and with ResPES techniques. The stoichiometry of each atomic species has been evaluated through a comparison with LAO and STO single crystals. A resonance enhancement of the conductive Ti states, associated to a small fraction of Ti3+ ions is reported and compared to theoretical calculations. On the basis of these results, the origin of metallic states in ultra-thin LAO-STO interfaces is properly addressed. In addition, a characterization of the intermixing and the disorder at the LAO-STO interface has been done through angle-resolved XPS, providing important information on the intermixing of light cations (Al, Ti) otherwise missed by X-ray diffraction techniques.
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Книги з теми "Oxide thin films and heterostructure"

1

France) International Conference on Thin Film Deposition of Oxide Multilayers Hybrid Structures (2nd 2001 Autrans. International Conference on Thin Film Deposition of Oxide Multilayers Hybrid Structures: TFDOM-2 : Autrans, France, October 18-19, 2001. Les Ulis, France: EDP Sciences, 2001.

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2

G, Schlom Darrell, ed. Epitaxial oxide thin films III: Symposium held March 31-April 2, 1997, San Francisco, California, U.S.A. Pittsburgh, Pa: Materials Research Society, 1997.

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3

K, Fork David, ed. Epitaxial oxide thin films and heterostructures: Symposium held April 5-7, 1994, San Francisco, California, USA. Pittsburgh, PA: Materials Research Society, 1994.

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4

Fanciulli, Marco, and Giovanna Scarel, eds. Rare Earth Oxide Thin Films. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/b137342.

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Mele, Paolo, Tamio Endo, Shunichi Arisawa, Chaoyang Li, and Tetsuo Tsuchiya, eds. Oxide Thin Films, Multilayers, and Nanocomposites. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-14478-8.

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Ezema, Fabian I., Chandrakant D. Lokhande, and Rajan Jose, eds. Chemically Deposited Nanocrystalline Metal Oxide Thin Films. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-68462-4.

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Schneller, Theodor, Rainer Waser, Marija Kosec, and David Payne, eds. Chemical Solution Deposition of Functional Oxide Thin Films. Vienna: Springer Vienna, 2013. http://dx.doi.org/10.1007/978-3-211-99311-8.

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8

Murphy, Thomas Patrick. Electrochromic properties of tin-nickel oxide thin films. Oxford: Oxford Brookes University, 1997.

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9

Elfallal, Ibrahim Abdel-Wahab. A study of indium tin oxide thin films. Salford: University of Salford, 1992.

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10

M, Durbin Steven, Wenckstern Holger von, Allen Martin W, and Materials Research Society, eds. Zinc oxide and related materials--2009: Symposium held November 30-December 3, 2009, Boston, Massachusetts, USA. Warrendale, Pa: Materials Research Society, 2010.

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Частини книг з теми "Oxide thin films and heterostructure"

1

Di Castro, Daniele, and Giuseppe Balestrino. "High T c Superconductivity in Engineered Cuprate Heterostructures." In Oxide Thin Films, Multilayers, and Nanocomposites, 39–68. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-14478-8_3.

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2

Ramesh, R., O. Auciello, V. G. Keramidas, and R. Dat. "Pulsed Laser Ablation-Deposition and Characterization of Ferroelectric Metal Oxide Heterostructures." In Science and Technology of Electroceramic Thin Films, 1–22. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-017-2950-5_1.

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3

Perniu, Dana, Cristina Bogatu, Silvioara Gheorghita, Maria Covei, and Anca Duta. "Thin Films Based on ZnO-Graphene Oxide Heterostructures for Self-Cleaning Applications." In Springer Proceedings in Energy, 435–47. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-55757-7_30.

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4

Pintilie, I., L. Pintilie, L. D. Filip, L. C. Nistor, and C. Ghica. "Oxide Thin Films and Nano-heterostructures for Microelectronics (MOS Structures, Ferroelectric Materials and Multiferroic Heterostructures)." In Size Effects in Nanostructures, 77–108. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-662-44479-5_4.

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5

Venkatesan, T., S. Bhattacharya, C. Doughty, A. Findikoglu, C. Kwon, Qi Li, S. N. Mao, A. Walkenhorst, and X. X. Xi. "Pulsed Laser Deposited Metal-Oxide Based Superconductor, Semiconductor and Dielectric Heterostructures and Superlattices." In Multicomponent and Multilayered Thin Films for Advanced Microtechnologies: Techniques, Fundamentals and Devices, 209–38. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1727-2_13.

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Fister, Tim T., and Dillon D. Fong. "In Situ Synchrotron Characterization of Complex Oxide Heterostructures." In Thin Film Metal-Oxides, 1–49. Boston, MA: Springer US, 2009. http://dx.doi.org/10.1007/978-1-4419-0664-9_1.

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7

Haavik, Camilla, and Per Martin Rørvik. "Conducting Oxide Thin Films." In Chemical Solution Deposition of Functional Oxide Thin Films, 621–54. Vienna: Springer Vienna, 2013. http://dx.doi.org/10.1007/978-3-211-99311-8_25.

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8

Mele, Paolo, Shrikant Saini, and Edoardo Magnone. "Thermoelectric Modules Based on Oxide Thin Films." In Thermoelectric Thin Films, 139–56. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-20043-5_7.

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Thimont, Yohann. "Thermoelectric Oxide Thin Films with Hopping Transport." In Thermoelectric Thin Films, 185–204. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-20043-5_9.

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Kim, Heungsoo. "Transparent Conducting Oxide Films." In Pulsed Laser Deposition of Thin Films, 239–60. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2006. http://dx.doi.org/10.1002/9780470052129.ch11.

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Тези доповідей конференцій з теми "Oxide thin films and heterostructure"

1

Krishnamoorthy, Sriram, Arkka Bhattacharyya, Praneeth Ranga, and Saurav Roy. "MOCVD-grown high-performance gallium-oxide thin films, heterostructures, and devices." In Oxide-based Materials and Devices XIII, edited by Ferechteh H. Teherani and David J. Rogers. SPIE, 2022. http://dx.doi.org/10.1117/12.2626507.

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2

Afanasjev, V. P., G. A. Konoplev, D. A. Chigirev, N. V. Mukhin, E. I. Terukov, and E. E. Terukova. "The formation of zinc and copper oxides thin films for heterostructure solar cells." In SPIE Photonics Europe, edited by Ralf B. Wehrspohn, Andreas Gombert, and Alexander N. Sprafke. SPIE, 2016. http://dx.doi.org/10.1117/12.2227421.

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3

Kim, Hye Ju, Seong Hwan Kim, and Sang Woon Lee. "Transistor Using Two-dimensional Electron Gas in Thin Film Oxide Heterostructure via Atomic Layer Deposition." In The 5th World Congress on New Technologies. Avestia Publishing, 2019. http://dx.doi.org/10.11159/icnfa19.134.

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4

Kim, Seong Hwan, Hye Ju Kim, and Sang Woon Lee. "Tailoring of Two-dimensional Electron Gas Density in Thin Film Oxide Heterostructure via Atomic Layer Deposition." In The 5th World Congress on New Technologies. Avestia Publishing, 2019. http://dx.doi.org/10.11159/icnfa19.135.

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5

Uddin, Ghulam Moeen, Katherine Ziemer, Abe Zeid, and Sagar Kamarthi. "Study of Lattice Strain Propagation in Molecular Beam Epitaxy of Nano Scale Magnesium Oxide Thin Film on 6H-SiC Substrates Using Neural Network Computer Models." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-87015.

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Анотація:
Magnesium oxide (MgO) is a candidate for interface layer application in multifunctional heterostructures. Molecular beam epitaxy (MBE) of MgO on 6H-SiC is studied for effective integration of functional oxides. In this research we present the neural network assisted design of experiment (DOE) analysis of the crystalline structure of MgO films grown over 6H-SiC substrates. Based on reflection high energy electron diffraction (RHEED) characterization of the MgO (111) films grown we present the DOE analyses of the strain propagation in two different orientations (110 and 112) during growth process with respect to growth time, substrate temperature, magnesium source temperature, plasma intensity and percentage oxygen on the starting surface of 6H-SiC substrates. We conducted constant substrate temperature (150°C) and constant plasma intensity (350mV) analyses to quantify the relation between lattice strains in <110> and <112> directions. The constant plasma intensity analysis reveals that the growth propagates in a tensile strain mode for well reconstructed SiC surface. However, excessive oxygen on the SiC surface causes the lattice of MgO twist due to tensile strain as seen from the <110> direction and compressive strain in <112> direction. In constant substrate temperature analysis we found that the principal tensile strain inducing variable in <110> direction is growth time and the strain continues to increase as the film grows thicker. However, in <112> direction the optimum plasma intensity is critical to maintain the optimum strain in the film structure.
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6

Wu, Naijuan, Y. S. Chen, S. Dordevic, and Alex Ignatiev. "Pyroelectric IR sensor based on oxide heterostructures on Si(100) and LaAlO3(100) substrates." In Third International Conference on Thin Film Physics and Applications, edited by Shixun Zhou, Yongling Wang, Yi-Xin Chen, and Shuzheng Mao. SPIE, 1998. http://dx.doi.org/10.1117/12.300682.

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7

Egbert, W. C., D. J. Gerbi, D. A. Ender, and J. Stevens. "Polymeric Heterostructure Thin Films." In 1988 Los Angeles Symposium--O-E/LASE '88, edited by Robert L. Gunshor. SPIE, 1988. http://dx.doi.org/10.1117/12.943964.

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8

Taniguchi, S., M. Yokozeki, M. Ikeda, and T. Suzuki. "Transparent oxide thin-film transistors using modulation-doped heterostructures." In 2010 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics, 2010. http://dx.doi.org/10.7567/ssdm.2010.p-6-16l.

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9

Jensen, Lars O., Frank Wagner, Mathias Mende, Céline Gouldieff, Holger Blaschke, Jean-Yves Natoli, and Detlev Ristau. "Defect formation in oxide thin films." In XLIII Annual Symposium on Optical Materials for High Power Lasers, edited by Gregory J. Exarhos, Vitaly E. Gruzdev, Joseph A. Menapace, Detlev Ristau, and M. J. Soileau. SPIE, 2011. http://dx.doi.org/10.1117/12.899113.

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10

Fan, Rui-Ying, Yue M. Lu, and Xiangyun Song. "Microstructure of titanium oxide thin films." In Shanghai - DL tentative, edited by Shixun Zhou and Yongling Wang. SPIE, 1991. http://dx.doi.org/10.1117/12.47278.

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Звіти організацій з теми "Oxide thin films and heterostructure"

1

Eng, Gabriel. Fabrication and Characterization of Gradient Oxide Thin Films. Portland State University Library, January 2016. http://dx.doi.org/10.15760/honors.281.

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2

Ramanathan, Shriram. Photo-Activated Synthesis of Functional Oxide Thin Films. Fort Belvoir, VA: Defense Technical Information Center, March 2010. http://dx.doi.org/10.21236/ada534012.

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3

Chow, A. F., A. I. Kingon, O. Auciello, and D. B. Poker. Investigation of optical loss mechanisms in oxide thin films. Office of Scientific and Technical Information (OSTI), May 1995. http://dx.doi.org/10.2172/86955.

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4

Carim, Altaf H. Microstructures and Epitaxy in Oxide Superconductor Thin Films and Devices. Fort Belvoir, VA: Defense Technical Information Center, March 1994. http://dx.doi.org/10.21236/ada278427.

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5

Olson, K. Laser photodeposition of molybdenum oxide thin films from organometallic precursors. Office of Scientific and Technical Information (OSTI), January 1990. http://dx.doi.org/10.2172/7186114.

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Apen, E. A., L. M. Atagi, R. S. Barbero, B. F. Espinoza, K. M. Hubbard, K. V. Salazar, J. A. Samuels, D. C. Smith, and D. M. Hoffman. New deposition processes for the growth of oxide and nitride thin films. Office of Scientific and Technical Information (OSTI), November 1998. http://dx.doi.org/10.2172/676883.

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7

Pejakovic, Dusan. Thin Films of Reduced Hafnium Oxide with Excess Carbon for High-Temperature Oxidation Protection. Fort Belvoir, VA: Defense Technical Information Center, February 2010. http://dx.doi.org/10.21236/ada514280.

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8

Vohs, John, Raymond Gorte, and Steve McIntosh. Enhancing Coking Tolerance and Stability of SOFC Anodes Using Atomic Layer Deposition (ALD) of Oxide Thin Films. Office of Scientific and Technical Information (OSTI), December 2021. http://dx.doi.org/10.2172/1837232.

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